Construction of transgenic plants is central to modern plant molecular
genetics. Inducible systems permit spatial and temporal control of
transgene expression. One commonly used inducible system relies on the
use of dexamethasone to activate an endogenously expressed hybrid
transcription factor, which positively regulates the expression of the
gene of interest (Aoyama and Chua, Plant J 11:605–612, 1997). We have
developed Arabidopsis plants using this inducible system to drive
expression of a bacterial type III effector protein. The effector,
AvrRpm1, elicits either strong cell death or weak cell death and
chlorosis depending on the genetic background of the plant. Using these
reagents, we examine several properties of the inducible system in
Arabidopsis, including the timing of induction, the ability to tune the
level of transgene expression by altering the concentration of applied
dexamethasone, and the movement of dexamethasone within the plant.